Zvex - '59 Sound  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
Post Reply
User avatar
Nocentelli
Tube Twister
Information
Posts: 2222
Joined: 09 Apr 2009, 07:06
Location: Leeds, UK
Has thanked: 1152 times
Been thanked: 954 times

Post by Nocentelli »

Yet another one bugg has posted on his site:

http://www.pedalpcb.com/docs/TweedSound.pdf

Box of Rock variant, with minor changes to cap values Q2/3 source resistors and D-G bias resistor of Q3 so would be quite possible to do a BoR/'59 Sound mode switch with a 4P3T rotary.

I like this more than i remember liking the BoR when i made one years ago, but i just don't like having a single BMP style tilt tone pot and am considering putting a Bassman tonestack on the end instead - If anyone has any advice/suggestions/experience of doing this, feel free to chip in.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

User avatar
HamishR
Breadboard Brother
Information
Posts: 78
Joined: 31 May 2016, 14:51
Has thanked: 6 times
Been thanked: 46 times

Post by HamishR »

I like this one a lot better than the BoR too. For a bass control I used IVIark's suggestion and swapped the 470K resistor in parallel with the 470pF cap on the base of Q2 for a 1M pot. It's not perfect but it works. It works better at cutting the bass than boosting it, but there's already plenty of low end in the circuit anyway. I used a linear pot and strangely enough 12.00 (approx 470K) seems to sound best to me!

In both stock version and modded version I would like a hair more midrange. If I could get a tiny bit more midrange in there this would be one of my favourite pedals - as it is it's very cool. Fantastic overdrive with a Gibson.

User avatar
bmxguitarsbmx
Cap Cooler
Information
Posts: 510
Joined: 25 Mar 2010, 21:15
Has thanked: 704 times
Been thanked: 216 times

Post by bmxguitarsbmx »

HamishR wrote:...
In both stock version and modded version I would like a hair more midrange. If I could get a tiny bit more midrange in there this would be one of my favourite pedals - as it is it's very cool. Fantastic overdrive with a Gibson.
Try increasing the value of the 470p cap. 1n or 2.2n will make the mids more aggressive (in Marshall amps atleast)

User avatar
ppluis0
Diode Debunker
Information
Posts: 915
Joined: 14 Jul 2010, 18:33
Location: Argentina
Has thanked: 127 times
Been thanked: 299 times

Post by ppluis0 »

Hi folks,

The BS170 has the same numbers in their datasheet than 2N7000 but they differ only in the pin assignment ?
I mean: by merely placed 180º rotated these two models of trannies are interchangeable ?

Cheers,
Jose

User avatar
HEAD
Resistor Ronker
Information
Posts: 442
Joined: 16 Dec 2008, 00:13
Location: Leipzig, Germany
Has thanked: 24 times
Been thanked: 49 times

Post by HEAD »

ppluis0 wrote:Hi folks,

The BS170 has the same numbers in their datasheet than 2N7000 but they differ only in the pin assignment ?
I mean: by merely placed 180º rotated these two models of trannies are interchangeable ?

Cheers,
Jose
In short: Yes.

User avatar
mirosol
Resistor Ronker
Information
Posts: 292
Joined: 11 Mar 2012, 16:15
my favorite amplifier: Been on Bogner for quite some time now.
Completed builds: Over 1000 and counting.
Location: TKU, FI
Has thanked: 192 times
Been thanked: 449 times

Post by mirosol »

Nocentelli: Possibly something like this? The BMP-tone is replaced with a stock Fender stack from Tonestack calc and followed by a recovery stage (as the stack takes more than 10db away) before the output filtering.

If i'm correct, this would make a decent fender amp emulation / drive pedal.
Attachments
FYA-WickerHead.sch.png
http://tagboardeffects.blogspot.com/
http://mirosol.kapsi.fi/
"No such thing as innocence" -Iron Chic

User avatar
HamishR
Breadboard Brother
Information
Posts: 78
Joined: 31 May 2016, 14:51
Has thanked: 6 times
Been thanked: 46 times

Post by HamishR »

That's a really interesting idea. That tonestack is more BF era Fender though - I would be more inclined to try a tweed style tone stack, which would use two 22n caps and a 250pF treble cap and a 56K slope resistor. Even though the 5F6-A Bassman schematic shows a .1uF and a .047uF cap in the tonestack they more often came with a pair of .022s. (And that's the tonestack Marshall initially adopted)

Thanks for the tip on the cap - I will try that. And I think Mirosol may be onto something. The stock pedal circuit sounds very good indeed so could be worth experimenting with.

User avatar
Nocentelli
Tube Twister
Information
Posts: 2222
Joined: 09 Apr 2009, 07:06
Location: Leeds, UK
Has thanked: 1152 times
Been thanked: 954 times

Post by Nocentelli »

HamishR wrote:I would be more inclined to try a tweed style tone stack, which would use two 22n caps and a 250pF treble cap and a 56K slope resistor.
Tried this and it was quite thin and hissy. I suspect the severe treble roll-off of the BoR/'59 sound/BSIAB2 helps mitigate the glassy quality of the 3xSHOs in series.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

User avatar
HamishR
Breadboard Brother
Information
Posts: 78
Joined: 31 May 2016, 14:51
Has thanked: 6 times
Been thanked: 46 times

Post by HamishR »

Hey Mr BMX - I removed the 470pF in parallel with the 470K resistor (which is actually a 1M pot in my latest version) and man - you have created a monster! I replaced the 470pF with a 2n2 and it's incredible. It has to be the most authentically JMP Marshall sound I have heard from a pedal. Wow. It is so much better than a Distortron it's crazy.

I guess if i was diligent I should put that cap on a switch so I can choose between 470pF (flatter mids, more '59 Bassman sounds) and the 2n2 (raucous old-school Marshall mayhem). But I think I'll just leave it as 2n2. :-) I have a stock '59 Sound to compare it to and I really like both. I do think Z Vex should stick that cap on a switch because I reckon plenty of players would LOVE the 2n2 cap sound.

It would even be cool as a stomp switch boost. The stock '59 Sound is such a great rhythm sound that being able to switch to the 2n2 would be a handy lead boost option. What I especially like is that the lows are still super punchy and tight. No mush and fuzz there. This pedal and P90s are a wonderful mix...

User avatar
bucksears
Solder Soldier
Information
Posts: 172
Joined: 08 Sep 2007, 23:02
Has thanked: 16 times
Been thanked: 41 times

Post by bucksears »

Bumping this one as I’ve got one about to start building.

Does that 1M bass pot mod affect the mids at all?
I’m sold on the idea of the mid stock/boost caps on a switch, but being able to roll off bass as well has my interest.
Just curious how much overlap/interaction there is, if any.

User avatar
KirkD777
Information
Posts: 1
Joined: 27 Mar 2023, 20:26
Has thanked: 2 times

Post by KirkD777 »

HamishR wrote: 26 Feb 2018, 06:52 Hey Mr BMX - I removed the 470pF in parallel with the 470K resistor (which is actually a 1M pot in my latest version) and man - you have created a monster! I replaced the 470pF with a 2n2 and it's incredible. It has to be the most authentically JMP Marshall sound I have heard from a pedal. Wow. It is so much better than a Distortron it's crazy.

I guess if i was diligent I should put that cap on a switch so I can choose between 470pF (flatter mids, more '59 Bassman sounds) and the 2n2 (raucous old-school Marshall mayhem). But I think I'll just leave it as 2n2. :-) I have a stock '59 Sound to compare it to and I really like both. I do think Z Vex should stick that cap on a switch because I reckon plenty of players would LOVE the 2n2 cap sound.

It would even be cool as a stomp switch boost. The stock '59 Sound is such a great rhythm sound that being able to switch to the 2n2 would be a handy lead boost option. What I especially like is that the lows are still super punchy and tight. No mush and fuzz there. This pedal and P90s are a wonderful mix...

Forgive the necro post, But I've been looking for an authentic JMP sounding pedal for years. Got my JMP stolen. My friend makes pedals. Can you post the mods you feel gets closest to that sound? Dont care about the 59 Bassman circuit. Just want to make it easy for him.

Thanks brother.

Post Reply